Method for producing hypochlorite solutions and introducing same into confined bodies of water



March 18, 1969 R. E. STANTON 3,433,723

METHOD FOR PRODUCING HYPOCHLORITE SOLUTIONS AND INTRODUCING SAME INTOCONFINED BODIES OF WATER Original Filed March 28, 1962 Sheet of 5 was 56i 64 I NVENTOR.

Ross/Pr E. STANTON ATTORNEYS AND Sheet INVENTOR.

ATTORNEYS IIIIIIIIIIIJ //////1 I/I/I/I METHOD FOR PRODUCING HYPOGHLORITESOLUTIONS INTRODUCING S ROBERT E. STANTON BY W,

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March 18, 1 969 R. E. STANTON 3,433,723 METHOD FOR PRODUCINGHYPOCHLORITE SOLUTIONS AND INTRODUCING SAME INTO CONFINED BODIES OFWATER Original Filed March 28, 1962 Sheet 3 of 5 v a w J Jaw/MM, yv zATTORNE Y5 1 I g INVENTOR.

/ ROBE/PT E. STANTON- BY March 1969 R. E. STANTON 3,433,723

ODIES OF WAT METHOD FOR PRODUCING HYPOCHLORITE SOLUTIONS INTRODUCINGSAME INTO CONFINED B Original Filed March 28, 1962 Sheet in? I NVENTOR.

ATTORNEYS March 18, 1969 R. E. STANTON 3,433,723

METHOD FOR PRODUCING HYPOGHLORITE SOLUTIONS AND INTRODUCING SAME INTOCONFINED BODIES OF WATER Original Filed March 28, 1962 Sheet 5' of 5INVENTOR. H6 I ROBE/PT E. STAA/Td/V United States Patent Ofiice 3 ClaimsABSTRACT OF THE DISCLOSURE A method of treating a confined body of waterby floating thereon an electrolytic cell containing a water solubleelectrolytically decomposable metallic chloride salt, adding water tothe salt to produce an electrolyte, transferring the electrolyte to thelower end of the cell which comprises an electrolysis zone partiallysubmerged in the confined body of water, decomposing the electrolyteelectrolytically to produce an hydroxide together with chlorine andhydrogen gases while simultaneously reacting the chlorine and hydroxideto produce the corresponding hypochlorite and introducing the thusproduced hypochlorite into the confined body of water.

This application is a division of application Ser. No. 183,242, file-dMar. 28, 1962, now US. Patent No. 3,222,- 269.

Untreated water employed for drinking or bathing purposes frequently maypresent a serious health hazard to individuals and to communities byreason of the biologically active contaminants, such as pathogenicorganisms, putrescent substances or the various plant growths containedtherein. In many instances these contaminants also will impartobjectionable odor, taste, color or turbidity to the water unless theyeither are removed or substantially reduced by appropriate treatment.

Many conventional methods used for treating biologically contaminatedwater are based upon the chemical action of chlorine or variouschlorine-releasing compounds. While the direct introduction of gaseouschlorine from a pressurized source probably represents the sim plestform of water treatment, this method has the dis advantages of requiringheavy and cumbersome pressuretype storage cylinders to contain thesupply of liquid or gaseous chlorine, and an expensive and delicatelybalanced metering system for regulating the delivery of the gas.

Chlorine-containing compounds such as granular solidtype hypochloritepreparations, generally will contain about 35% available chlorine, buthave the disadvantage of being difficult to distribute uniformlythroughout a large volume of water in addition to being quite costly.

Domestic type laundry bleach solutions containing 3% to 5% availablechlorine as sodium hypochlorite also may be used for this purpose,although they share equal disadvantages with the solid hypochloritepreparations in being both an expensive source of chlorine and difficultto introduce in uniform proportions into large volumes of untreatedwater.

The hypochlorites used for water treatment purposes ordinarily areproduced by reacting gaseous chlorine with a hydroxide of sodium,potassium or calcium, under carefully controlled conditions. Thechlorine, together with the desired hydroxide compound are readilyobtainable by simple electrolysis of an aqueous solution of thecorresponding chloride salt. For example, a sodium chlo- 3,433,723Patented Mar. 18, 1969 ride brine may be electrolyzed to form chlorineand sodium hydroxide according to the equation:

The chlorine and sodium hydroxide obtainable from the electrolysis ofsodium chloride brine may be reacted at temperatures below 35 C. toyield sodium hypochlorite according to the equation:

2NaOH+Cl =NaOCl+NaCl+H O 2 Unless the heat of the latter reaction isdissipated rapidly, the temperature of the system may exceed 35 C.,which promotes the formation of objectionable chlorate compoundsaccording to the equation: I

3NaOCl (heat) =NaClO +2NaCl (3) Chlorate formation may represent asubstantial loss of valuable hypochlorite product from the system, sincethe chlorates are not particularly effective in the treatment ofbiologically contaminated water.

The cost of manufacturing sodium hypochlorite bleach solutions fordomestic consumption in accordance wit-h reactions (1) and (2) may bequite nominal, although the delivered costs of the product invariablywill be high, due to the common practice of producing aqueous solutionscontaining about of water and other inert substances and the necessityfor packaging and transporting the highly corrosive liquid in expensiveglass or plastic containers which conform with interstate shippingregulations.

An average family size swimming pool containing 15,000 to 25,000 gallonsof water, ordinarily will require dosing with about 5 to 10 gallons perweek of domestic laundry bleach solution during the periods of activeuse, in order to maintain the purity of the water within acceptablelimits. Usually, this dosing consists simply in dumping the contents ofone or more standard 1 gallon jugs of bleach solution into the pool,followed by prolonged periods of stirring or circulating the water topromote an effective distribution of the hypochlorite therein, and toavoid any localized concentrations of the reagent which could beinjurious or irritating to the eyes or skin of bathers. Furthermore, themetal pool fixtures may be severely corroded by contact with the dumpedhypochlorite bleach solution before a proper degree of dilution has beenachieved, and the pool ordinarily must be vacated by bathers until thedosing and mixing procedures have been reasonably completed.

All of the above mentioned disadvantages, together with otherobjectionable features relating to the purification of biologicallycontaminated water with hypochlorite solutions, either can be avoided orgreatly alleviated by the use of my invention as herein illustrated anddescribed.

Briefly, my invention permits the purification of relatively largevolumes of water to be achieved conveniently and economically bycontinuously producing electrolitically a hypochlorite solution from abrine consisting of a small portion of the water being purified and anappropriate chloride salt, and thereafter introducing the hypochloritesolution into the substantially larger remaining portion of the waterbeing treated at a rate approximately equal to the rate of hypochloriteformation so that excessive concentration of the latter is avoided. Theseveral steps comprising my invention preferably are conductedimmediately below the surface of the volume of water brine treated inorder to dissipate the heats of the reac tions therein and to maintainthe temperatures within a range which avoids substantial formation ofchlorates.

Proper regulation of the electrolysis step allows only about one-half ofthe chloride salt to be converted into reaction products, so that theconductivity of the electrolyte does not become lowered to a point whichwould adversely affect the rate of the efficiency of the conversion.Accordingly, the hydroxide product becomes dissolved in the unreactedone-half of the brine and is withdrawn from the electrolysis cells insolution, while hydrogen and chlorine are generated in the reaction in agaseous form and will bubble upwardly through the liquid. My inventionemploys the kinetic effect of the rising gas bubbles in a mannerhereinafter disclosed, to produce the required flow of reactants andproducts throughout the entire sequence of operating steps without theuse of conventional pumping or circulating devices.

Any chlorides of the alkali or alkali-earth groups which are commonlyrecognized in the art as sources of electrolytic chlorine andhydroxides, also may be employed for identical purposes in the practiceof my invention, although I prefer to use ordinary table salt, or sodiumchloride, on account of its low cost, availability, and high degree ofchemical stability which assures relatively safe and convenienthandling.

Table salt frequently is supplied for household purposes in disposablecardboard cartons which contain about two pounds of finely granulatedsalt product. One of the embodiments of my invention employs apparatushereinafter described and illustrated, which can be adapted to receive acharge of salt in the form of an unbroken carton or package.

It is, therefore, the principal object of my invention to provide anovel method and apparatus for continuously purifying contained bodiesof water such as, for example, in swimming pools and the like.

A second objective of the instant invention is the provision of aminiaturized hypochlorite production plant designed to be floated in thebody of water the hypochlorite produced thereby is to purify.

Another object is to provide means of the class described capable ofcontinuously generating a supply of hypochlorite and simultaneouslyintroducing same into the water to be treated therewith.

Still another objective of the invention herein disclosed is to providea miniaturized production facility of hypochlorite which utilizes thewater being treated as one of the reactants and also as a heat sink tocontrol the heat of reaction.

An additional object is the provision of apparatus for the production ofhypochlorite that utilizes the kinetic energy of the gaseous reactionproducts to accomplish the desired flow and circulation of the reactantsthrough the several processing stages.

Further objects of my invention are to provide a hypochlorite productionmethod and apparatus that are economical both from the standpoints ofinitial cost and operating expense, a system which avoids localized highconcentrations which might be injurious to persons and equipment, a unitthat is compact and can be left floating in the water being treated atall times due to its decorative appearance, and apparatus specificallyadapted to accept common table salt in ordinary cardboard containers asthe source of chloride ion.

Other objects will be in part apparent and in part pointed outspecifically hereinafter in connection with the description of thedrawings that follows, and in which:

FIGURE 1 is a top plan view illustrating a multi-celled embodiment of myhypochlorite production apparatus;

FIGURE 2 is a fragmentary section taken along line 22 of FIGURE 1illustrating the electrolytic cell configuration;

FIGURE 3 is a fragmentary section taken along line 3-3 of FIGURE 1showing another view of the cell;

FIGURE 4 is an enlarged fragmentary section taken along line 44 ofFIGURE 1 showing the chamber in which the salt brine is produced;

FIGURE 5 is a fragmentary section taken along line 4 55 of FIGURE 1illustrating the discharge by means of which the hypochlorite isintroduced into the water being treated;

FIGURE 6 is a top plan view to a reduced scale showing the apparatus ofFIGURE 1 mounted in the floating ring that provides the supporttherefor;

FIGURE 7 is a side elevation of the apparatus of FIG- URE 6;

FIGURE 8 is a vertical section similar to FIGURES 4 and 5 showing asingle-celled embodiment of the apparatus;

FIGURE 9 is a side elevation of a further modified form of the apparatusthat utilizes a different type of electrolytic cell;

FIGURE 10 is a top plan view of the cell of FIGURE 9;

FIGURE 11 is an enlarged fragmentary section of the modifiedelectrolysis cell of the FIGURE 9 modification; and,

FIGURE 12, is a schematic representation of the apparatus of FIGURE 9.

Referring now to the drawings for a detailed description of the presentinvention, and initially to FIGURES 6 and 7 for this purpose, referencenumeral 14 designates in a general way a miniaturized hypochloriteproduction facility which is attached to a float 16 that supports samein a confined body of water 18. The float 16 may consist of any buoyantmaterial capable of supporting the apparatus in water; however, it iscontemplated that one of the several rigid forms of polystyrene orpolyurethane molded into the shape of a hollow ring will be used forthis purpose.

As the description proceeds, frequent reference will be made to the bodyof water undergoing treatment as the source of water for dissolving thesalt, the electrolysis reaction, the cooling medium and the buoyantsupport for the apparatus as this is the simplest and most efficientform of the invention. It is to be clearly understood, however, that thebody of water performing the abovementioned significant functions may,if desired, be entirely separate from the body of water requiringpurification. For example, by floating the apparatus in a separate tubof water and discharging only the product into the pool, any objectionthat bathers might have to swimming in a pool containing electricalapparatus would be eliminated.

Basically, the apparatus involved in the production of hypochlorite fromwater and a chloride-containing salt by electrolysis consists of a brinetank and one or more electrolytic cells that have been broadlydesignated by reference numerals 20 and 22, respectively. The cells 22are preferably arranged in a ring around the inside of the floatsurrounding the brine tank 20. This entire assembly including the brinetank, cells and float is floated on the surface of the water beingtreated, the latter forming the source of the water required in theelectrolysis reaction and also the coolant that prevents the formationof the bothersome quantities of the chlorate.

The reaction is initiated in the brine tank 20 which will now bedescribed in detail with reference to FIG- URES 1 and 4. In theparticular form shown, the tank comprises an open-topped hollowcylindrical vessel 24 that is preferably molded out of plastic to reducethe cost thereof, render it lightweight and eliminate the necessity forinsulating same from the electrolysis cells and associated conductors.The vessel 24 is supported by the float so that all but the top thereofis submerged in the water to be treated. Water enters the brine tankthrough one or more vented passages 26 that open beneath the surface ofthe water. A branch passage 28 has its inlet connected into passage 26beneath the vent and the level to which the water rises therein so as toconduct the water into the bottom of the brine tank where its outlet islocated. In the form shown in FIGURES 1 and 4, riser passage 26 andsealed passage 28 are molded within ribs 30 that project from theexterior of the tank; however, it is obvious that a vented riser pipe26a and seal pipe 28a could also be used for the same purpose such ashave been shown in FIGURE 8.

In the interests of simplicity, vessel 24 is sized to receive anordinary cardboard salt container 32 of the type obtaina'ble from almostany grocery store. By using common table salt in packaged form, much ofthe inconvenience associated with the filling of the tank and cleaningsame are eliminated. The container 32 will, of course, becomewater-logged almost immediately upon immersion in the tank; therefore, awire basket 34 is preferably provided to facilitate insertion andremoval. This basket, as shown, provides a grid 36 adapted to supportthe bottom of the container, an overhanging portion 38 positioned tooverlie the top of the container and prevent it from floating to the topof the tank, and a handle forming portion 40 which facilitates liftingthe spent salt container from the tank. As illustrated,vertically-disposed grooves 42 are provided in the walls of the vessel24 which slidably receive vertical elements of the basket and preventrelative rotation therebetween.

In order to insure that the Water issuing from the outlet of passage 28percolates through the salt confined within the container 32 rather thanflowing upwardly around the outside of the latter, means are providedadjacent each outlet in the base of the tank to puncture the containerand subsequently hold the punctured aperture open. Such means includes apair of horizontally-spaced essentially vertical cutters 42 havingdownwardly and inwardly inclined knife edges 44 on their upperextremities in position to cut into the bottom and cylindrical sidewallof the descending salt container thus separating a tab therefrom alongtwo sides. These cutters are disposed adjacent each outlet of thepassages 28 on opposite sides thereof. Obviously, by merely cutting atab free of the container along two sides does not, in itself, insure anopening of sufficient size to allow the water to enter freely;therefore, the cutters are supplemented by inwardly bowed elements 46located therebetween in overlying relation to the outlet of passage 28.These bowed elements cooperate with the cutters to push the tab freed bythe latter inwardly thereby allowing the water to enter the container.In the particular form shown herein, elements 46 comprise spring memberssecured to the wall of vessel 24 along their top edges only, thusleaving the lower edges free to slide downwardly along said wall in amanner to straighten out the bow therein as the bottom of the containerpasses alongside into final position resting on grid 36 of basket 34.Note in this connection that overhanging portion 38 of the basketprevents the carton 34 from rising as it contacts the cutters andassociated bowed element.

The untreated water entering the bottom of tank 20 flows into the bottomof the salt container through the openings punched therein percolatingup through the salt bed and out through previously-opened pouring spout48 to produce a supernatant layer of substantially saturated sodiumchloride brine 50 (FIGURE 8) rising about two inches above the top ofthe carton or salt bed as determined, of course, by the depth to whichthe float allows the brine tank to sink. While common table salt is preferred as a source of the chloride ion and the action of the hydroxideneeded for the electrolysis step, as has already been mentioned, otheralkali and alkaline-earth chlorides capable of being reactedelectrolytically to release gaseous chlorine are also satisfactory.Therefore, even though repeated reference will be made to sodiumchloride as one of the principal reactants, it is to be understood thatsuch statements are intended as being merely illustrative of one of theseveral chloride-containing salts that can be used and that theinvention is by no means restricted to its use alone.

An outlet 52 is provided in the wall of the brine tank at a levelsomewhat below that to which the water rises on the outside of the tankthus permitting the brine to overflow into a trough-like tray or plenum54 which is shaped to deliver same to the first of the electrolyticcells 6 22. The construction and arrangement of these cells can best beseen in FIGURES l, 2 and 3 to which reference will now be made for adetailed description thereof.

A more compact structure results when several cells are employed byarranging them in a more or less circular or polygonal pattern aroundthe periphery of the brine tank as indicated in FIGURE 1. All of thecells may be identical and are preferably constructed of a suitablecorrosion resistant moldable plastic material which requires noinsulation. In fact, the cells and brine tank can be molded on the sameplastic material in the form of a more or less single-piece unit.

The cells are of a unique design in that they provide for a steadilyincreasing cross-sectional area from the bottom to a point near the topfor a purpose which will be outlined presently and they also includemeans by which the escaping gases are utilized to stir up the watersurrounding the apparatus thus providing more efiicient heat transfer.The cells of FIGURES l, 2 and 3 include a pair of spaced substantiallyparallel side walls 56 of inverted generally triangular shape that arejoined together along their edges by a pair of downwardly and inwardlyinclined end walls 58 and 60. In order to group the cells in a polygonalarrangement around the periphery of the brine tank, the end walls 58 and60 are not parallel as wall 58 is located at the corner in the mannershown in FIGURE 1. A partial partition -wall 62 is provided in each cellextending between the side walls 56 and cooperating with end wall 52 todefine a downwardly and inwardly inclined passage 64 of substantiallyuniform cross section. Partition 62 projects above the liquid level inthe cell thus separating the interior thereof into two compartments tointerconnect with one another at their lower ends where partition 62terminates short of the bottom of the cell. The upper end of passage 64of the first cell in the series opens into plenum 54 to receive brinedirectly from the brine tank. The lower margin of partition wall 62 isformed to provide an upturned portion 66 which receives the lower edgeof anode 68 that extends upwardly along the inside of said partition.The anode is fabricated from a fiat strip of carbon or other suitableanode-forming material. While graphite carbon plates are acceptable forboth electrodes, it is preferable to employ plates of someelectrically-conductive material coated with a layer of lead dioxidesuch as are used in automobile storage batteries. An anode is, ofcourse, provided in each of the cells. The anode 68m in the first cellof the series is modified slightly to include an integrally-formed lug70 to which the electrical conductor 72 is attached.

The opposing inner face of end wall 60 is fitted with the cathode 74which is similarly retained in place by upturned integrally-formed lip76 provided on the inner face of wall 60 near the lower extremitythereof. These lips 66 and 76, of course, maintain the anodes andcathodes 0f the cell separated from one another. If, as shown, the cellsare fabricated from a non-conducting plastic material, no furtherinsulation is necessary.

The cathode of the first cell is electrically connected to the anode ofthe second cell by a bus bar 78, the cathode of the second cell to theanode of the third, and so on until the last cell of the series isreached whereupon its anode is connected to a conductor 80. Conductor 80is connected to the negative terminal of a suitable direct current powersupply 82 (FIGURE 8) while conductor 72 is connected to the positiveside thereof.

Before continuing with the detailed description of the cell structure,it would be well to explain briefly the current requirements of theprocess and how they may best be satisfied. The current must bedelievered to the cells at a potential of between approximately 3.2 and4.0 volts which, if a single electrolytic cell is used, would require acomplicated and expensive current source due to the heavy amperageneeded. It is, therefore, preferable to utilize a multiple-cellinstallation in which several smaller cells are connected together inseries to form a cascade thus accomplishing the electrolysis insuccessive steps at correspondingly lower amperages.

A safe level at which to supply current to apparatus of the typedescribed herein when used in a swimming pool is about 16 volts. Apotential of this magnitude is not dangerous to swimmers even thoughthey come into direct contact with the current-carrying elementsthereof. By utilizing a 16 volt current supply, four cells in seriessuch as are shown in FIGURE 1 can be used to advantage. Alternatively, aseries-parallel circuit with two or more banks of fourserially-connected cells with the banks wired in parallel can be used.

Ordinarily, direct current will be supplied to the cells so that theanode and cathode elements maintain their respective positive andnegative polarities at all times; however, for purposes of the presentinvention it is desirable, under certain conditions, to reverse thepolarities of the electrodes to avoid polarization of their surfaces dueto the formation of gas films thereon. Such reversal of the electrodepolarities even at frequent intervals has no adverse effect upon theelectrolysis reaction since the anode and cathode products must becombined to form the desired hypochlorite product within the system. Asa practical matter, rather than using a battery as indicated at 82 inFIGURE 8 as the source of direct current, it will usually be supplied inthe form of ordinary alternating household current through a transformerto a dry-type selenium or silicon rectifier which will convert same todirect current at the desired potential before delivering same to thecells. It is a simple matter to anchor the apparatus near the side ofthe pool for purposes of supplying power thereto from an outlet in thenear vicinity.

Returning once again to FIGURES 1, 2 and 3 in order to complete thedescription of the cell construction, note the unique arrangement of theanode-cathode pairs in opposed upwardly divergent relationship to oneanother. This is quite useful in carrying out the electrolysis reactionas the ascending mixture of liquid and gaseous products formed betweenthe electrodes progress upwardly at a relatively uniform rate. In otherwords, the brine overflowing plenum 54 enters passage 64 of the firstcell, flows downwardly in the latter and emerges in the space betweenthe electrodes at their point of closest approach to one another,whereupon, gas bubbles begin to form immediately and steadily increasein number as the mixture ascends and continues to react. Thus, byspreading apart the electrodes at their upper ends, the progress of themixture is not retarded due to the build-up of bubbles as it rises.

As the brine ascends in the cell, the electric current passing betweenthe electrodes converts the brine into hydrogen and sodium hydroxide atthe cathode and chlorine at the anode. The rising volume of gaseousproducts that forms between the electrodes forces the supernatantliquids upwardly and, in so doing, causes unreacted portions of thebrine to react in the same manner at progressively higher levels therebyproducing additional liquid and gaseous reaction products. At thispoint, it should be mentioned that these reaction products, particularlythe sodium hydroxide and chlorine, and to a lesser extent the sodiumhypochlorite, are injurious to many substances; therefore, the cellsmust be fabricated from a material which will resist this corrosiveaction such as, for example, unplasticized polyvinyl chloride.

The mixture of liquid and gaseous reaction products has a substantiallylower density than the incoming brine solution so that the reactionmixture will rise higher in the cell than the level maintained by theincoming brine solution. For this reason, the mixture of reactionproducts will have a sufficient hydrostatic head due to its higher levelto overflow into the inclined passage 64 of the second cell. Not all ofthe brine is reacted in the first cell of the series, therefore, thesame reaction takes place in the other cells resulting in the desiredlow density mixture capable of successive migration through the entireseries.

The vigorous interaction of the liquid and gaseous components of thereaction mixture as they ascend in the cells causes a chemicalcombination between the chlorine gas and the sodium hydroxide to producethe desired end product, namely, sodium hypochlorite. Hydrogen gas,therefore, remains as the only gaseous component reaching the top of thecell in substantial quantities. The reaction mixture remains as a frothor foam at the top of the cell, whereupon, the gaseous and liquid phasesseparate from one another with the sodium hypochlorite and unreactedbrine overflowing into the second cell while the hydrogen gas is takenoff through exhaust tube 86.

This exhaust tube 86, one of which is provided in each cell, also formsan important and novel part of the cell. Lids 89 are provided for eachcell extending between adjacent partition walls 62 and the side wallsthus forming an essentially gas-tight closure over the cell to preventthe escape of gas therefrom except by means of exhaust tube 86. Theseexhaust tubes open through one of the side walls of the cell and extenddownwardly therefrom into the water being treated where they terminateadjacent the exterior surface of the cell. It has already been mentionedthat undesirable quantities of chlorate compounds will be produced ifthe temperature of the system exceeds C. The electrolysis reaction is anexothermic one and the heat thus generated can easily raise thetemperature of the system to a point above the 35 C. maximum; therefore,some means for holding the temperature at or below this figure should beprovided. It is this function which is performed by exhaust tube 86which delivers the escaping hydrogen gas into the water adjacent thecell and causes same to circulate more or less continuously much in themanner of a pump. Of course, by continuously agitating the water in theimmediate vicinity of the apparatus, the cells are constantly subjectedto the cooling effects of the water which dissipates the heat ofreaction and then moves away.

The substantially gas-free brine which flows across the upperHume-forming edge 88 of end wall enters the passage 64 of the secondcell where it is subjected to further electrolysis. Successive portionsof the brine are reacted in each cell until approximately one-half ofthe brine has been converted into sodium hypochlorite in the cellseries.

A product consisting of approximately one-half sodium hypochlorite andone-half sodium chloride dissolved in the proportion of about 30% totalsolids in water, flows across the flame-forming edge 88 of the last cellinto sink. 90.

This sink, which is most clearly revealed in FIGURES 1 and 5, is open atthe top and has a rim 92 on three sides thereof which, in cooperationwith partition wall 88 of the last cell, encloses a bottom 94 thatslopes in all directions toward a drain 96. The underside of the drain96 has attached thereto a flexible hose 98 that extends downwardlytherefrom to the depth beneath the surface of the body of water at whichit is desired to introduce the hypochlorite. By locating the outlet ofdrain tube 98 adjacent one of the water inlets of the pool, the incomingwater will insure reasonably uniform distribution of the purifyingreagent throughout the entire volume of water contained therein.Actually, it is often possible to vary the rate at which the waterenters the pool to correspond approximately with the rate of productionof the hypochlorine solution to facilitate relatively uniformdistribution of the purifying agent.

Now, it is possible that substantial quantities of water in the brinesolution will be lost through chemical or electrolytic decomposition atit progresses through the several cells; therefore, in order to preventthe percentage of solids from becoming unduly high in the brine, it maybe desirable to dilute the solution by adding water thereto at someintermediate stage of the reaction. For this purpose, vented passage 26mlocated between cells two and three of the series is provided with aport 100 opening onto the outer surface of the unit underneath the Waterlevel but above the level of the brine in the adjacent downwardlysloping passage 64 into the bottom of the third cell. This outlet 100supplies water for diluting the brine to the third cell at the same timepassages 26 and 28 are supplying water to the brine tank.

In the production of sodium hypochlorite according to the equations setforth earlier, it will be seen that about half of the sodium hydroxideobtained by the electrolysis of salt in Equation 1 is again reconvertedinto the original salt when the hydroxide is reacted with chlorine toform sodium hypochlorite in accordance with Equation 2. Since both ofthese reactions occur about simultaneously in the electrolytic cells,the salt produced byEquation 2 merely recycles internally within thecell system to combine with the incoming brine and again is convertedinto the hydroxide by the reaction of Equation 1 until the repeatedsequence of operations has converted the original salt charge into thedesired yield of hypochlorite product.

Next, with brief reference to the more or less schematic representationof the unit shown in FIGURE 8, it will be noted that similar elementsfunctionally to those already described in connection with FIGURES 1-7,inclusive, have been identified by corresponding reference numerals towhich the postscript a has been added for purposes of denoting theirslight structural differences where such are present. For example,passages 26a and 28a have been shown in the form of pipes or tubesrather than molded passages. Brine tank 24a is considerably simplifiedin that it includes no provision for accepting the salt container andforming openings therein, but instead, is designed to receive a chargeof salt that is merely poured therein.

As for the cells 22a, they are also very similar to the ones alreadydescribed and the elements of which they are comprised perform identicalfunctions, by way of example, the end walls 58a and 60a are slightlydifferent at their lower ends and wall 60 and partial wall 62a do notinclude the upturned portions 66 and 76 (FIGURE 1) that restrain thelower ends of the electrodes. The overflow arrangement 88a is slightlydifferent as is the design of the sink 90a, 92a and 94a. Exhaust tube86a is shown emerging from the top 89a rather than from a sidewall,however, this again, has no functional significance.

There are, however, a few refinements shown in FIG- URE 8 which have notbeen described before or illustrated in FIGURES 1-7 although they areequally applicable thereto. The first of these is the aspirator 102shown in dot-dash lines. The purpose of this bulb-type aspirator is tomanually pump brine from the tank into the first cell in the event thelatter has filled with water while the apparatus is being readied foruse but before it has actually been placed in operation. In other words,as soon as the unit is placed in the water, the brine tank will fill andwater will overflow into the first cell even though no salt has beenadded to form the electrolyte which is necessary to start and sustainthe reaction. Means for transferring the brine to the first cell of theseries is, therefore, a convenient accessory.

A pilot lamp 104 shunted into the power supply to the cells is also auseful addition to the system for purposes of indicating that theelectrolyte is sufiiciently conductive to permit an adequate flow ofcurrent. Of course, other signalling devices well known in the art maybe employed for the same purpose.

One other point should be mentioned briefly in connection with theschematic representation of the unit shown in FIGURE 8. In this figure,only a single electrolytic cell has been shown in full lines; however,additional cells have been shown in dotted lines to indicate anothertype of multiple-cell arrangement that could be employed. In otherwords, instead of grouping the several cells in a ring about the tank,they could be strung out in a line so that the outlet 96 of theintermediate cells would drain into the downwardly inclined passage 64of the nextcell in the series. Of course, the last cell would be fittedas shown in full lines with the discharge tube 98 through which the 10hypochlorite solution would be fed into the water being treated.

Finally, with reference to FIGURES 1-9, inclusive, a furthermodification of the miniaturized hypochlorite production apparatus willnow be described in detail. The major modification lies in the differentcell construction 22b when compared with the one already described. Inthe schematic representation of FIGURE 12, the modified cell 22b will beseen to comprise a substantially vertically disposed down-comer tube 64bwhich corresponds to the downwardly and inwardly inclined passage 64 ofthe previously-described cell design, an upwardly inclined metal tubecomprising the cathode of the cell, a carbon rod 106 disposed coaxiallywithin the metal tube 104 to form the anode, a chamber 108 at the upperterminus of the tube 104 and a gravity-type delivery tube 98b whichdelivers the hypochlorite reaction product to the water being treatedfollowing separation of the gaseous constituent therefrom in chamber108. Thus, from the brine tank 20b, the brine flows down down-comer 64binto the lower end of upwardly inclined cathode 104 where it issubjected to the electrolysis reaction as it flows upwardly into thechamber 108. As before, the level of the reaction mixture in chamber 108is somewhat higher than the corresponding brine level in brine tank 20bdue to the presence of substantial quantities of the gaseousconstituents which cause the mixture to take on the character of a frothor foam. In chamber 108 the hydrogen gas and small residual amounts ofchlorine separate from the liquid phase. The liquid phase, consisting ofthe hypochlorite reaction product and any unreacted brine remaining aredrawn off the bottom of separating chamber 108 by the discharge tube98b.

The electrolyte, of course, flows upwardly in the annular space 110between the anode and cathode-forming elements 104 and 106. The leadfrom the negative side of the direct-current power supply is connecteddirectly to the metal tube 104 that comprises the cathode; whereas, thelead 72 from the positive side of the power supply extends downwardlyinside the cathode tube through insulator 112 to anode rod 106 which isdisposed within the lower portion of the cathode. Accordingly, theelectrolysis reaction is confined to the lower portion of inclined tube104 where the anode is located and the upper portion of this tube whichcontains the insulators 112, constitutes a mixing zone where the sodiumhydroxide and chlorine generated in the electrolysis step combine toproduce the hypochlorite reaction product.

FIGURES 9, 10 and 11 illustrate the manner in which cell 22b can be usedwith a brine tank 20b similar in most respects to the brine tank 20 ofFIGURE 4. Brine tank 20b includes the vented riser passage 26, passage28 communicating therewith and with the interior of the ,tank tointroduce the water into the bottom of the tank and such other features(not shown) as the wire basket, means for puncturing the salt containerand spring clip to hold the punctured aperture open as may be desired.Vertically disposed down-comer 64b is connected into the wall of thetank in position to draw off the brine therefrom and carry it downwardlyinto the lower end of cathode forming tube 104. i

This cathode tube is preferably formed of stainless steel while theanode 106 is again preferably carbon. All of the remaining parts of theapparatus with the exception of the conductors, conductor terminals andthe like are non-conducting plastic as before.

The preferred arrangement is to wind the cathode tube spirally aroundthe outside of the brine tank as shown most clearly in FIGURE 9. This,of course, necessitates a flexible anode, one form of which has beenillustrated in FIGURE 11.

The lower end of the cathode tube is connected to the corresponding endof down-comer 6% by a conventional hose coupling 114. The upper end issimilarly connected to separation chamber 108 which is attached to thebrine tank in position such that the low-density foaming reactionmixture can rise therein to a level somewhat above the level of thebrine in the tank 2011. A terminal 116 is attached to the wall of thecathode tube for purposes of detachably receiving the negative conductor80.

The positive conductor 72 is connected to a currentcarrying cable 118which extends downwardly through the cathode tube and carries current tothe anode 106. Current-carrying cable 118 is insulated from tube 104 andchamber 108 throughout its entire length. Chamber 108, being fabricatedfrom plastic, is no problem although in the particular form shown itincludes a partition-forming portion 120 that contains an opening 122housing an insulator 124 through which the stainless steel cable passes.The insulators 124 are plastic or some other suitable insulatingmaterial and are disposed at spaced intervals throughout the length ofthe stainless steel cable 118.

In the particular form shown, these insulating elements 124 are more orless circular having a diameter slightly less than the inside of tube104. They have one or more notches 126 in their periphery to permit thefree flow of the reaction mixture in annular space 110. Opposite facesof the insulating disks are provided with hemispherical depressions 128bordering the central cable opening 130 therein and these depressionscooperate with the rounded ends 132 of the elongated carbonanode-forming elements 106 and correspondingly shaped insulators 134 toproduce a flexible ball-and-socket connection. The lower extremity ofthe stainless steel cable 118 is provided with a balltype anchor element136 which articulates within the adjacent depression in insulator 124.

The shape of carbon anode elements 106 and insulator elements 134 issubstantially identical although obviously only the carbon elements willconduct current to the electrolyte. Therefore, these carbonanode-forming elements are located on approximately the lower half ofthe stainless steel cable 118 where the electrolysis reaction is to takeplace and the non-conducting insulating elements 134 are confined to theupper end of the cable where the chemical reaction between the sodiumhydroxide and chlorine is to take place.

The modification of FIGURES 9-12, inclusive, is considerably morecompact than that previously described; however, it is somewhat moredifficult to adapt to a multiple-cell operation.

Having thus described the several useful and novel features of my methodand apparatus for producing and introducing hypochlorite solutions intocontaminated water, it will be seen that the several worthwhileobjectives for which it was designed have been achieved. Although but afew specific embodiments of my invention have been illustrated anddescribed in connection with the accompanying drawings, I realize thatcertain intention that the scope of protection afforded hereby shall belimited only insofar as such limitations are expressly set forth in theappended claims.

What is claimed is:

1. The method of purifying a confined body of water which comprises thesteps of:

floating an electrolytic cell comprising a contained quantity of awater-soluble and electrolytically-decomposable metallic chloride salton a body of water; adding water to said salt to produce a brine;transferring said brine to the lower end of said cell, said lower endbeing an electrolysis zone partially submerged in said confined body ofwater;

decomposing the brine electrolytically to produce an hydroxide togetherwith chlorine and hydrogen gases while simultaneously reacting saidchlorine and hydroxide chemically to produce the correspondinghypochlorite; and,

introducing the thus produced hypochlorite into the confined body ofwater.

2. The method as set forth in claim 1 including the step of dischargingthe uncombined gaseous reaction products underneath the surface of saidwater and adjacent the electrolysis zone, said discharging gas formingmeans adapted to circulate said water adjacent said electrolysis zonethereby dissipating the heat generated in the latter.

3. The method of purifying a confined body of water which comprises thesteps of floating a contained quantity of a water-soluble andelectrolytically-decomposable metallic chloride salt in an electrolyticcell on a body of water, continuously adding successive portions of saidconfined water to the salt to produce a brine, transferring the brine tothe lower end of said cell forming an electrolysis zone which ispartially submerged in said confined water, decomposing the brineelectrolytically to liberate chlorine and hydrogen gases along withsodium hydroxide, releasing the hydrogen gas into said confined wateradjacent the electrolysis zone in a manner to cause said confined waterto circulate and dissipate the heat developed by the chemicalcombination of the chlorine and sodium hydroxide and producing thehypochlorite, and introducing the hypochlorite into the water requiringpurification.

References Cited UNITED STATES PATENTS 892,486 7/1908 Woolf 204149 XR1,079,377 1l/l913 Swinburne 204149 1,200,165 10/1916 Burgess 2041492,701,790 2/1955 Goument 204 XR 3,223,242 12/1965 Murray 210-62 XR3,274,094 9/1966 Klein 204149 XR ROBERT K. MIHALEK, Primary Examiner.

G. KAPLAN, Assistant Examiner.

